1. Field of the Invention
The invention relates to an endoscope observation device, an observation device and an observation method using the endoscope.
This application is based on Japanese Patent Application No. 2006-046639, the content of which is incorporated herein by reference.
2. Description of Related Art
Generally, a fluorescent endoscope system for observing the fluorescence generated by irradiating the excitation light to a live body tissue has been disclosed by Japanese Unexamined Patent Application, Publication No. 10-243920 (hereinafter referred to as Patent Document 1), for example.
The aforementioned fluorescent endoscope system is structured to irradiate the excitation light to a live body, and to detect the fluorescence naturally emitted from the live body or the fluorescence from the medicine which has been infused to the live body in the form of two-dimensional images. The fluorescent endoscope system allows the diagnosis of the disease, for example, degeneration of the body tissue or cancer based on the detected fluorescent image.
In order to accurately detect the degree of malignant of the cancer cell and the like, the absolute value of the quantity of the fluorescence emitted by the body tissue has to be accurately obtained. The quantity of the fluorescence received by a light receiving portion disposed at a tip of an insertion portion varies as the distance between the tip of the insertion portion and a specimen such as the body tissue. It is therefore indispensable to establish the process for obtaining the absolute value of the fluorescent quantity irrespective of the fluctuation as described above.
Patent Document 1 discloses the fluorescent endoscope system equipped with a distance measurement unit using ultrasonic signals for measuring the distance between the tip of the insertion portion and the specimen.
Japanese Unexamined Patent Application, Publication No. 11-148897 discloses an optical imaging apparatus using the technique to irradiate the low coherence light to the specimen such that the accurate tomogram of the specimen is obtained from the information of the light scattered in the specimen, that is, OCT (optical coherence tomography) technique.
The distance measurement unit using the ultrasonic wave may work only when the space from the ultrasonic wave oscillator to the specimen is filled with water. It is not capable of measuring the distance of the space filled with air.
The generally employed OCT technique has been used only to form the tomogram of the specimen.